1. Field of the Invention
The present invention relates to an information processing device and an external unit applicable to the information processing device.
2. Description of the Related Art
In recent years, an information processing device having a display unit serving also as inputting means is known as a portable information processing device. For example, in an information processing device allowing an operator to input with a stylus, a transparent touch panel is provided on the upper surface of the display unit. By making the tip of the stylus into contact with the touch panel, information is input or inputting with a keyboard additionally used is associated.
In this kind of information processing device, expandability is generally considered. In a notebook personal computer, for example, a slot is formed on a side surface of its housing. By inserting a PC card into this slot, a memory capacity can be increased or the connection with a network can be facilitated.
The term of PC card is a general term for credit-card sized peripheral equipment conforming to the “PC Card Standard” planned by a joint effort between PCMCIA (Personal Computer Memory Card International Association) and JEIDA (Japan Electronic Industry Development Association).
Some kind of desktop personal computer also supports a PC card.
There are several types of PC cards such as SRAM, flash memory, hard disk, modem, SCSI, and LAN cards.
The PC cards are typically classified into three types different in thickness. Type 1 is 3.3 mm thick, and it is mainly used for memory cards. Type 2 is 5 mm thick, and it is mainly used for I/O features such as modems. Type 3 is 10.5 mm thick, and it is mainly used for hard disks, etc.
As an expansion card suitable for further size reduction, a CF (Compact Flash) card is sometimes used. The CF card is used as a compact card compatible with a flash ATA memory card in a digital camera, portable personal computer, PDA, etc. The size of the CF card is 42.8×36.4×3.3 (mm), which is smaller in each dimension than the PC card. For example, a CF card having a maximum memory capacity of 48 megabytes has been provided by SanDisk Corporation, U.S.A.
Recently, a thicker CF card having a thickness of 5 mm has also been used. The increase in thickness allows the addition of I/O features, thereby providing applicability to modems, LAN cards, SCSI cards, etc.
In the case of connecting a notebook personal computer through a LAN network to the Internet, a wireless LAN module as a PC card is sometimes inserted into a PC card slot provided in the computer to effect wireless connection. In this case, however, an antenna of the wireless LAN module projects from the body of the computer, so that there is a possibility of damage to the antenna or the card itself.
It is considered that the wireless LAN module is preliminarily set as an internal option in the computer. However, it is not easy to change options.
Further, another type of wireless LAN module adapted to USB connection is also commercially available. However, this type of wireless LAN module has a unique connector and therefore lacks versatility.